The interaction of metal carcinogens with human peripheral lymphocytes is under investigation. Initially we seek to determine whether DNA repair enzymes which may be involved in the excision-repair of metal-induced DNA lesions are induced during lymphocyte stimulation by phytohemagglutinin. The uracil DNA glycosylase is induced 10 fold as a function of lymphocyte stimulation Treatment with either Actinomycin D or with cycloheximide prevented enzyme induction and decreased glycosylase activity at maximal stimulation.